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Review The Power of Internet Mapping by Kyle Bohnenstiehl Internet map server (IMS) applications allow GIS database custodians to easily make their spatial data accessible through a web browser interface to end users. High speed corporate intranets make an ideal network for distributing data in this manner given the fact that bandwidth requirements can be high. Making data available to the entire world is certainly feasible and any organization that has a public website can certainly add an IMS without opening up too many additional security holes. The most basic IMS display vector and image data in a simple web interface with zoom, pan, and print functions. Advanced interfaces let users change the symbology of vector data, add new layers from local or internet data sources, edit and subset vector data, generate cartographic quality map layouts, make measurements and create buffers. Complex Active-X and Java web browser interfaces may demand too much bandwidth for some Internet users; applications should be carefully tailored for the end users available bandwidth. MapInfo, Autodesk, and ESRI all produce a full-featured IMS software application. Users can take the software out of the box and have an IMS site up and running in a matter of hours if they have all of the required components available to them including a compatible web server and servlet engine. The options for customization, both on the server and client side, are numerous but this article will focus on using the basic products as they ship out of the box. In addition, the Minnesota Department of Natural Resources (MDNR) distributes their free MapServer software over a website and users can be up and running in several hours following their instructions. Standard Internet protocols allow any device that can access internet sites to become a spatial information portal, anywhere in the world. PDA''s, pocket PC''s, satellite and cellular phones can all function as GIS data viewers and allow users access to useful or even life saving information. The transparent, platform independent nature of Internet Mapping makes your GIS data available to constituents, stakeholders, and interested parties in a low cost, paperless, and fully customizable environment. How IMS Software Works Internet mapping software requires two components to function. A geospatial data processing engine that runs on the server side as a service, servlet or CGI application, and processes the raw spatial data into a map is the first. The second component is a standard web server that manages the incoming requests and replies with the proper map data back to the client side browser or application window. The end product is either a JPEG or GIF image that is transmitted back to the client browser or a stream of data that is interpreted by a plug-in to the client browser. IMS that transmit back only an image have a limited capability that doesn''t extend much beyond pan, zoom, and basic vector attribute query. The feature streaming IMS requires a downloadable plug-in but allows for advanced buffer, query, labeling and subsetting operations to be performed. Some IMS sites offer both a plug-in and a simple HTML version, which is nice for plug-in weary surfers. Data can be stored locally on a dedicated internet server, on network drives or even on a 3rd party IMS like ESRI''s Geography Network. Raster and vector data is supported by most IMS applications along with full database integration for advanced SQL operations. Compressed Mr. Sid and ECW imagery works very well in IMS applications and can speed up server side processing considerably. If your data is only going to be available on an internal corporate intranet, then concerns about bandwidth and outside world connectivity are minimized. However, IMS that serve data up to the entire world will require a good connection to the Internet that is reliable and has the proper hardware for security and routing. A static IP address with a valid DNS entry is required for most web servers on the internet, so budget and plan accordingly to obtain these two items. Most web hosting companies are not set up for IMS hosting so your best bet is to run the server inside your building where you can control, update and restart it when required. Some companies do offer dedicated IMS hosting of your spatial data. See www.merrick.com for a description of their IMS hosting services. As with any software today, there are many choices for platforms, operating systems, servlet engines, web server software, and pricing. Prospective customers should thoroughly evaluate all of the functions they will require to find the best product and if possible run the software in demonstration mode before purchasing. The Power of Internet Mapping Continued… If you are dealing with DWG CAD drawing files, MapGuide®. could be the way to go for making them available on the web. Full support for raster imagery, DXF and other popular vector formats allow this CAD product to serve up maps that look like they came from a GIS. The free Autodesk MapGuide®. Viewer is required to get the full functionality of the application on the client side but it runs with Netscape and Internet Explorer on Windows, Macintosh and Sun. Autodesk MapGuide®. LiteView requires no plug-in and is a platform independent viewing solution. Engineering and architectural firms with clients world-wide will appreciate the ability to digitize, markup and redline maps and designs from the browser window. Integration with Autodesk OnSite®., the Pocket PC CAD software allows field personnel with a wireless internet connection to be a part of the design and review process, a function that could be useful on remote or complicated projects. Other features include full support for Oracle 9i spatial databases, a full-featured suite of IMS application development tools, and support for Active X, API, Microsoft COM, HTML, Java, JavaScript, VBScript and XML tools. SSL support keeps out unwanted users and provides security for clients data. Perhaps the strongest feature of MapGuide is the cartographic tools. Sophisticated maps with symbol X/Y offsets, symbol size definition, Autodesk Map line types, legends, scale bars, north arrows, custom titles and more are possible. For people needing serious power to deliver complex data, MapGuide looks like an excellent choice.
ArcIMS 3.1 offers a well-developed set of tools for creating out of the box or highly customized IMS applications. HTML image viewers or complex Java, Cold Fusion or Active Server Page clients can be built using ESRI''s templates or from scratch. The ArcIMS manager software allows for easy web based configuration of sites, map servers, and services from one tool. ArcIMS functions with a wide variety platforms, operating systems, web servers, and servlet engines. Compatbility with Arc SDE and ArcGIS 8.1 make it a natural choice for GIS groups that use these applications. One of the best features of ArcIMS is the strong developer network that exists and ESRI''s excellent knowledge base and FAQ sections online at www.esri.com. The ArcIMS XML language is easy to master, well documented, and is very powerful, allowing for almost anything you can think of to be programmed as an IMS application. There are several add-on modules to ArcIMS 3.1 like routing software that is very useful for real-time fleet tracking and dispatching applications. Extensive data sets ship with some products allowing for detailed driving directions IMS applications to be served up right out of the box. Other ESRI products that are released or are being planned include:
Overall, ArcIMS is a well developed, industry standard product that will do basic IMS mapping right out of the box, but lends itself to extensive customization.
Mapinfo MapXtreme Java Edition This product is a full-featured GIS IMS package that has a powerful set of tools for the developer. A Rapid Prototyping module is supposed to save developers time in developing applications and any Java J2EE application server is supported. It ships with the Apache Tomcat 3.2 servlet container saving users some money upfront. Mapinfo is making the product available for download for a free 30-day trial from their website at www.mapinfo.com. In addition to the Java version, there is also a regular Windows OS version. Some nice features of MapXtreme include a save state object which allows developers to revert to any view that a user previously prepared. For example, what layers were turned on, how far the view was zoomed in, and what they were looking at can all be referenced using an object rather than writing code to revert to that view. Advanced legend, labeling, and thematic functions allow for professional quality cartography in a simple web interface. Rather than having all of the labels in one font, labels can be displayed in various fonts, colors or sizes driven by values in the database. MapXtreme supports MapInfo TAB files and .gst files in addition to a number of other popular formats. Supported file formats include Oracle Spatial, SpatialWare for SQL Server, SpatialWare for Informix, Spatial Ware for DB2, MrSID compression format, ECW compression format, ADRG, CADRG, CIB, ASRP and NITF raster formats.
MapServer: The free IMS If the commercial packages are giving you a case of sticker shock, then you should look at the Minnesota Department of Natural Resources Map Server 3.5 software. It is available at http://mapserver.gis.umn.edu/ and offers lots of FAQ''s, support and user developed tools to get you up and running. A CGI script version makes it easily transportable to dedicated ISP/Web Hosting servers and it can use PHP, PERL, CGI scripts and Apache compilers to make it truly a low cost solution. It also supports links to the popular MySQL database. This free IMS offers the following functionality:
While lacking some of the commercial features, this free application will get your data on the web and help you deliver high quality maps quickly, if you follow the easy instructions. You will need administrator privileges on your internet server to install MapServer (or any other IMS) properly. 
Figure 4
Data Value Added Large investments in data, both vector and raster, have been made by many groups. Enabling the public, your co-workers, your boss, and even you to access this data with a simple, easy to use, platform independent browser helps leverage a little more value from your data. Giving managers the ability to come in and look at a project area they may be unfamiliar with is a great tool. Also, IT people do not have to distribute and install another application to all users; everyone already has a web browser and knows how to use it. Adding IMS hyperlinks in reports can add new dimension to what is otherwise a boring document. Overall, IMS software has become very mature, mainstream and an essential element of any GIS operation. Kyle Bohnenstiehl has been involved in remote sensing, GPS and GIS for over 10 years and is currently a remote sensing scientist with the Department of Interior. His work has taken him throughout the Andes of South America and the desert Southwest where he has worked with tribes, NGO''s, government and private sector groups to create innovative solutions using the latest geotechnology. He can be reached at Kyle@nagis.com |
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